In the present investigation,the syntheses of some 12-substituted derivatives of camptotheoin, namely, 12-vitro-(Ⅴ),12-amino-(Ⅵ), 12-hydroxy-(Ⅹ),12-methoxy-(Ⅺ),12-oyano-(Ⅻ), 12-carboxy-(ⅩⅢ),12-carbomethoxy-(ⅪⅤ) and 12-mercapto-(ⅩⅤ) oamptothecin were described.The position of the substituent was determined with the aid of NMR spectroscopy. Camptothecin (Ⅰ) was nitrated in sulfuric acid to give V, of which catalytic hydrogenation led to the formation of Ⅵ.Diazotization of Ⅵ, followed by suitable transformations gave the desired compounds (ⅦⅩⅤ).Preliminary,pharmacological tests revealed that VIII showed much stronger inhibition against L-615.Ⅹ and Ⅺ exhibited stronger inhibition against Ehrlioh ascites carcinoma than Ⅰ.Further pharmacological examination is in progress.